Cylindrical roller bearings are known which include retainers adapted to be guided by the raceway surface of the outer ring or of the inner ring in contact therewith as disclosed in U.S. Pat. No. 3,675,292. The roller bearing of this type has the feature of being relatively smoothly movable during the rotation of the bearing since the retainer is guided by the raceway surface. However, the retainer involves sliding friction between the race riding surface thereof and the riding land for the retainer, in addition to the sliding friction which occurs between the rollers and the pocket defining surfaces of the retainer. The increased surface area giving rise to sliding friction results in a rise in the temperature of the bearing and causes greater wear on the retainer. The resulting heat generation and particles of worn metal act to accelerate the degradation of the lubricant. The sliding surfaces are prone to thermal adhesion which renders the bearing inoperative earlier. Especially when the bearing is installed in a tilted position, thermal adhesion is liable to take place between the race riding surface of the retainer and riding land therefor.
U.S. Pat. No. 3,647,273 discloses a roller bearing comprising retainer rings and space bar members which are made as separate pieces, such that rollers are first inserted into pockets and the retainer rings and the spacer bar members are thereafter connected together with rivets or like means. This roller bearing is cumbersome to assemble because the retainer rings and the space bar members, which are separate from each other, must be assembled. Additionally, when the roller bearing incorporating the resulting retainer is used under severe conditions as at a high rotation speed, the connecting portions are susceptible to loosening, damage or like trouble. Thus, the retainer of this type has the drawback of having low rigidity.
Cylindrical roller bearings are so designed that one of the inner and outer bearing rings is detachable as desired, such that when the inner ring, for example, is removed, the remaining parts including the outer ring, rollers and retainer will be held assembled as a unit, because the assembled unitary structure renders the bearings very advantageous to handle for transport or installation into machines. To ensure this advantage, the retainer must be provided with means for retaining the rollers in its pockets once the rollers have been placed therein.
When such bearings are installed into machines, the detached inner ring and the assembly of the outer ring, rollers and retainer are assembled into a bearing as installed in place. However, with bearings in which the rollers are movable by a great amount radially of the bearing, it is extremely difficult and therefore takes much time to fit the inner ring or rotary shaft in place. In order to reduce the radial movement of the rollers, there arises the necessity of positioning the roller retaining means close to the pitch circle of the rollers to the greatest possible extent, but if the retainer is so designated, the radial distance between the space bar member and the roller retaining means reduces, with the inevitable result that the retainer ring will have a smaller radial dimension and limited strength.
In brief, with retainers heretofore known, it has been extremely difficult to design means by which the rollers can be held on the retainer without being allowed to drop off the retainer radially of the bearing while the retainer is being handled after the rollers have been placed in the pockets of the retainer and also to design means for adjusting the movement of the rollers radially of the bearing when the bearing is to be installed into a machine so as to render the bearing easy to install.